Since NSA whistleblower Edward Snowden began leaking information seven months ago, the American public has learned a lot about government spying conducted on American soil, but much less about its surveillance activities around the world, which necessarily sweep up communications of Americans. The American Civil Liberties Union intends to change that by shedding light on Executive Order 12,333. Signed by President Ronald Reagan in 1981 and modified since, EO 12,333 covers government surveillance of Americans’ international communications—but the government’s interpretation of it is secret.

The ACLU filed a Freedom of Information Act (FOIA) lawsuit on the last day of 2013 demanding that seven government agencies respond to the ACLU’s May 2013 Freedom of Information Act request to search for and release documents related to EO 12,333, including ones that indicate how the government interprets the powers and limitations it sets forth.

Claiming that the government is relying on EO 12,333 to collect “nearly 5 billion records per day on the location of cell phones, including Americans’ cell phones; hundreds of millions of contact lists or address books from personal email and instant messaging accounts; and information from Google and Yahoo user accounts as that information travels between those companies’ data centers located abroad,” the ACLU complaint seeks “to determine what protections are afforded to those U.S. persons and whether those protections are consistent with the Constitution.”

Observing that “unchecked surveillance authority can lead to dangerous overreach,” the ACLU argues that there is no outside supervision of EO 12,333 surveillance, which is outside the jurisdiction of the FISA Court and is “not meaningfully overseen” by Congress. A member of the Senate Intelligence Committee staff toldThe Washington Post that 12,333 spying does “not fall within the focus of the committee.” Keith Alexander, director of the NSA, told a Judiciary Committee hearing he could not confirm that Congress is ever informed of 12333 activities.